Standard techniques to either deliver a fully relaxed or a defect free fin-type FET (FinFET) device include a strain relaxed buffer (SRB) or a fin condensation (e.g., oxide snowplow). However, these standard techniques cannot both yield a fully relaxed film and a defect free substrate. For example, a fully strained epitaxial SiGe growth can be made completely defect-free as deposited. However, when epitaxial (epi) growth parameters or post-deposition processing is introduced to relax the film, defects are incorporated that can result in performance degradation.
A need therefore exists for a methodology enabling preservation of the defect-free nature of the initial fully strained epitaxial growth of SiGe, while relaxing the SiGe and the resulting device.